Canto responded to Singer's tweet with a reply, "Thrilled to be X-Men," confirming that he's indeed on board the project without specifically telling the role he would play. He once hinted that his new project would have him "turn into a ball of fire if someone pisses [him] off." Thus, he is predicted to play either Brazilian mutant Roberto da Costa a.k.a. Sunspot or Japanese mutant Shiro Yoshida a.k.a. Sunfire.

"Days of Future Past" will be based on Uncanny X-Men #141 and 142 back in 1981 during Chris Claremont and John Byrne's run. The story introduced the idea of an alternate future for the Marvel mutants that grew out of the Brotherhood of Evil Mutants killing an important senator, leading to a future where all mutants are hunted by Sentinels.